I have three seats.
1. 550F seat, 9 out of 10, small hole on top, I put a nickel next to it for comparison. no rust
2. 550F seat, needs new cover, surface rust under seat.
3. 550K seat, needs new cover
Best to text at 704-7-six-3-5-two-11. Best to Paypal. SHOOT ME AN OFFER ON ANY OF THEM. Thanks